Relief-alidade.



F. H. C(LBURN.

RELIEF ALIDADL APPLICATION FILED JULY 25. l9'6v 1,240,676. PatentedSept.18, 1917.

2 SHEETS-SHEET 1.

8' Tm H r F. H. COLBURN.

RELIEF ALIDADE. APPLICATION m n JULY 25 19:6.

Patnted Sept. 18,1917.

0 2 SHEETS-SHEET 2.

UNITED srn'rns PATENT onrron FREDERICK H. COLBURN, OF CONCCBD, NENHAMPSHIRE, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE GOVERNMENT OF THEUNITED STATES AND THE PEOPLE THEREOF.

RELIEF-ALIDADE.

Specification of Letters Patent. Patented Se t 18, 1917 Applicationfiled July 25, 1916.

Serial No. 111,203.

(DEDICATED TO THE PUBLIC.)

To all whom it may concern:

Be it known that I, FREDERICK H. CoL- BURN, a citizen of the UnitedStates of America, residing at Concord, in the county of Merrimack,State of New Hampshire, whose post-office address is Concord, NewHampshire, have invented a new and useful Improvement in Relief-AlidadesThis application is made under the act of March 3, 1883, chapter l-fl3(22 Stat. 625), and the invention, herein described and claimed, may beused by the Governmentof the United States, or any of its officers oremployees, in the prosecution of work for the Government, or any personin the United States, without payment to me of any royalty thereon.

My invention relates to relief alidades.

The object of my invention is to provide an apparatus, simple inconstruction and easy of operation, and one which is specially designedto reproduce a panorama from a given point, upon a field sheet, justasit appears to the observer at, that point. It is particularlyuseful'in making the paneramic portion of a mountain look-out map.

The object, characteristic features, and scope of my invention will bemore readily understood from the following description, taken inconnection with the accompanying drawings, wherein:

Figure l is a side elevation.

Fig. 2 is a top plan view of the base.

Fig. 3 is a detail view of the front sight.

Fig. 4 is a vertical longitudinal section of the front sight.

Fig. 5 is a detail view of the rear sight.

Fig. 6 is a vertical longitudinal section of the rear sight.

Fig. 7 is a perspectiveview showing the maps.

Fig. 8 is a plan view showing the maps.

Referring to the drawings, A represents the base of the alidade, havinga projecting pivot B, firmly securedv thereto, which fits into a bushinga, in the center of the drawing board, C, in'such position as to permitthe base,A, to be revolved on said pivot,B. Said base, A, is partlyrecessed or cut away to the center line, as shown at b in Fig. 2. Thisrecessed portion is divided into suitable graduations, as shown at 0,Fig. 2.

The base, A, supports a spirit level, D,

and has threaded apertures, (Z, for receiving the setscrews hereinafterreferred'to. "Two small bosses, e, projecting from the underside of saidbase, A, together with the collar, 6, hold the base, A, parallel to andaway from, the drawing board, C. Y

A front sight, E, is pivotally hinged to one end of the base, A, bymeans of a spring hinge, f. Secured tothe base, A, is a post,

F, having an opening, 9, for receiving the quadrant, G, which quadrantis securely fastened to the front sight, E. The holes,

9, receive the stop, it, therebyv regulating the angle of the frontsight, E, with reference to the horizontal plane. The front sight, E,has'a tube, H, in which is adjusted a movable member, I, having itsupperpora recording is secured to the tube, H. The part, '5', is

attached to the thumb nut, L, by solder, or

other suitable means, the object being toprovide means for the thumbnut, L, to rotate freely about the tube, H, without movinglongitudinally thereon.

.The rear sight, M, is rigidly attached to the base, A, by set screws,7', which engage the threaded holes, (Z. The rear sight, M,

comprises an upright hollow tube, N, the

inside diameter of which is made of the proper size to receive a movablemember, C.

The member, 0, consists of a peep sight,P,

and the thumb screw, 76, which moves up and down in slot, Z, allowingthe member, O, to bc-clamped in any-of the positions regulated by thegraduations ofv the tube, N. The raising and lowering of the memher, 0,regulates the height of the peep sight, P.

In practising my invention, I [place the drawing board, C, on anordinary tripod, and place on the drawing board, C, a circular piece ofdrawing paper, with a radius slightly longer than the distance from thecenter pin, B, to the forward sight, E. In the interior of the paper Iplace a circular base map of the region around the mountain, thepanorama of Whichis desired, and leave a margin of uncovered paper aboutthree inches in width. Then I orient the table according to the interiorbase map and set up the alidade for use by inserting the pin, B, in thehole in the center of the drawing board, C.

The alidade is first adjusted so as to include within the sightinglimits of the alidade all of the panorama visible. This is accomplishedin the following manner: With the front sight, E, extended to its limit,I sight through the rear peep sight, P, and raise or lower the sight, P,until the highest point on the skyline is gotten into line of sight,when the member, 0, should be secured by tightening the thumb screw, is;then I return the member I into the tube, H, as far as it will o andsight again through the rear peep sight, P, to ascertain how much of thenear country is included in the range of sight. If it is desired toinclude more of the near country than this adjustment will permit, thenthe peep sight, P, should be raised, which action will serve, however,to sacrifice the showing of some of the high peaks on the panoramic map.This difficulty can in most cases be obviated by advancing the member,M, so that the set screws, 7', engage a pair of the threaded apertures,(Z, nearer the center of the base, A. To avoid distortion of thepanorama, the peep sight, P, must be left in one position until eachparticular map is finished. As a means of testingthe level andorientation of the board as well as the position of the drawing board.C, and the position of the rear sight, M, during the work, direct thealidade successively at several different peaks around the horizon; ineach instance bring the front sight, K, into the line of sight of therear peep sight, P, depress the front sight, E, causing-the needle, J,to make a small hole in the recording sheet and label this hole with thename of the peak sighted at. The front sight, E, is usually placed at anangle of t5 to the horizontal. If a larger angle is used, the panoramaappears flat; if a smaller angle is used, the panorama is exaggeratedvertically. Then starting at some convenient point, it is merelynecessary for the operator to sight at successive points along thevarious topographic elements visible from his station,

rotating the alidade and elevating or depressing the front sight, K. tobring it into line with the rear peep sight, P, and depressing the frontsight, E, at each sighting to cause the needle, J, to register. In thismanner the salient elements of relief of the particular topographicfeatures sighted at will be recorded on the map sheet as a series of pinholes, which, as the work progresses, are joined by a line to completethe relief sketching of those elements. These operations are continuedthroughout and around the whole field of vision of the operator in suchdegree of detail as circumstances Warrant. The operation is illustratedin Fig. 7 by m n 0 '0.

From the foregoing, it is thought that the construction, operation andmany advantages of the herein described invention will be apparent tothose skilled in the art, without further description, and it will beunderstood that variouschanges in the size, shape, proportion, and minordetails of construction maybe resorted to without departing from thespirit or sacrificing any of the advantages of the invention.

Having thus described my invention, I claim:

1. An alidade comprising a base adapted to be revolubly mounted on adrawing board, a tube hingedly connected to one end of said base,adjustable-means to hold said tube yieldingly in predetermined inclinedrelation to said base, saidtube being provided with a slot, a sightmember slidably 1nounted in said tube and having a marking deviceextending through said slot, a second tube adapted to be fixedly securedin different positions on said base, means for detachably securing saidsecond tube in said base, a sight adjustable in said second tube, andmeans to secure said sight in adjusted position in said second tube.

2. An alidade comprising a base, a front sight pivotally connected tosaid base, means connecting said base and sight normally to maintain thesight yieldably inclined to the base, and a vertically adjustable rearsight adapted to be fixedly and vertically secured in differentpositions on said base.

In testimony whereof. I aiiix my signature in the presence of twosubscribing witnesses.

FREDERICK H. COLBURN. Witnesses:

l/VM. J. Arman,- Jr., E. C. Hms'r.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

